U.S. patent application number 13/719875 was filed with the patent office on 2013-06-20 for epoxy resin composition for encapsulating semiconductor device and semiconductor device encapsulated with the same.
The applicant listed for this patent is Seung HAN, Ju Mi KIM, Eun Jung LEE, Sung Su PARK. Invention is credited to Seung HAN, Ju Mi KIM, Eun Jung LEE, Sung Su PARK.
Application Number | 20130158165 13/719875 |
Document ID | / |
Family ID | 48610764 |
Filed Date | 2013-06-20 |
United States Patent
Application |
20130158165 |
Kind Code |
A1 |
HAN; Seung ; et al. |
June 20, 2013 |
EPOXY RESIN COMPOSITION FOR ENCAPSULATING SEMICONDUCTOR DEVICE AND
SEMICONDUCTOR DEVICE ENCAPSULATED WITH THE SAME
Abstract
An epoxy resin composition for encapsulating a semiconductor
device and a semiconductor device encapsulated with the
composition, the composition including an epoxy resin; an inorganic
filler; a curing accelerator; and a curing agent, the curing agent
including a compound having a multifunctional novolac structure
including at least one biphenyl moiety, the compound being
represented by Formula 1: ##STR00001## wherein n is about 1 to
about 10.
Inventors: |
HAN; Seung; (Uiwang-si,
Gyeonggi-do, KR) ; KIM; Ju Mi; (Uiwang-si,
Gyeonggi-do, KR) ; PARK; Sung Su; (Uiwang-si,
Gyeonggi-do, KR) ; LEE; Eun Jung; (Uiwang-si,
Gyeonggi-do, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HAN; Seung
KIM; Ju Mi
PARK; Sung Su
LEE; Eun Jung |
Uiwang-si, Gyeonggi-do
Uiwang-si, Gyeonggi-do
Uiwang-si, Gyeonggi-do
Uiwang-si, Gyeonggi-do |
|
KR
KR
KR
KR |
|
|
Family ID: |
48610764 |
Appl. No.: |
13/719875 |
Filed: |
December 19, 2012 |
Current U.S.
Class: |
523/452 ;
523/400; 523/455; 523/457 |
Current CPC
Class: |
C08K 3/36 20130101; C08G
59/621 20130101; C09D 163/00 20130101; C09D 163/00 20130101 |
Class at
Publication: |
523/452 ;
523/400; 523/455; 523/457 |
International
Class: |
C09D 163/00 20060101
C09D163/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2011 |
KR |
10-2011-0138667 |
Claims
1. An epoxy resin composition for encapsulating a semiconductor
device, the composition comprising: an epoxy resin; an inorganic
filler; a curing accelerator; and a curing agent, the curing agent
including a compound having a multifunctional novolac structure
including at least one biphenyl moiety, the compound being
represented by Formula 1: ##STR00015## wherein n is about 1 to
about 10.
2. The epoxy resin composition as claimed in claim 1, further
comprising a non-halogenated flame retardant.
3. The epoxy resin composition as claimed in claim 2, wherein the
epoxy resin composition includes: about 1 to about 13% by weight of
the epoxy resin, about 74 to about 94% by weight of the inorganic
filler, about 0.001 to about 1.5% by weight of the curing
accelerator, about 0.001 to about 10% by weight of the
non-halogenated flame retardant, and about 1 to about 15% by weight
of the curing agent.
4. The epoxy resin composition as claimed in claim 2, wherein the
non-halogenated flame retardant includes at least one of
phosphazene, zinc borate, aluminum hydroxide, and magnesium
hydroxide.
5. The epoxy resin composition as claimed in claim 1, wherein the
curing agent has a hydroxyl equivalent weight of about 100 g/eq to
about 350 g/eq.
6. The epoxy resin composition as claimed in claim 1, wherein the
curing agent has a melt viscosity of about 0.08 poise to about 3
poise at 150.degree. C.
7. The epoxy resin composition as claimed in claim 1, wherein the
curing agent has a softening point of about 50 to about 140.degree.
C.
8. The epoxy resin composition as claimed in claim 1, wherein the
compound represented by Formula 1 is present in the composition an
amount of about 1 to about 15% by weight, based on a total weight
of the epoxy resin composition.
9. The epoxy resin composition as claimed in claim 1, wherein the
curing agent further includes at least one additional compound, the
additional compound including two or more phenolic hydroxyl
groups.
10. The epoxy resin composition as claimed in claim 9, wherein the
compound represented by Formula 1 is present in the composition in
an amount of about 30% by weight or greater, based on a total
weight of the curing agent.
11. The epoxy resin composition as claimed in claim 9, wherein the
additional compound includes at least one of a phenol aralkyl type
phenolic resin, a phenol novolac type phenolic resin, a xyloc type
phenolic resin, a cresol novolac type phenolic resin, a naphthol
type phenolic resin, a terpene type phenolic resin, a
multifunctional type phenolic resin, a multiaromatic phenolic
resin, a dicyclopentadiene type phenolic resin, a terpene-modified
phenolic resin, a dicyclopentadiene-modified phenolic resin, a
novolac type phenolic resin synthesized from bisphenol A and
resorcinol, a polyhydric phenolic compound, an acid anhydride, and
an aromatic amine.
12. The epoxy resin composition as claimed in claim 9, wherein the
additional compound includes at least one of: a phenol aralkyl
curing agent having a novolac structure represented by Formula 6:
##STR00016## wherein, in Formula 6, n is about 1 to about 7, a
xyloc curing agent represented by Formula 7: ##STR00017## wherein,
in Formula 7, n is about 1 to about 7, or a multifunctional curing
agent represented by Formula 8: ##STR00018## wherein, in Formula 8,
n is about 1 to about 7.
13. The epoxy resin composition as claimed in claim 1, wherein the
epoxy resin and the curing agent are included in the composition in
an amount such that a ratio of an epoxy equivalent weight of the
epoxy resin to a phenolic hydroxyl equivalent weight of the curing
agent is about 0.3:1 to about 2.5:1.
14. A semiconductor device encapsulated with the epoxy resin
composition as claimed in claim 1.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority under 35 U.S.C.
.sctn.119 to Korean Patent Application No. 10-2011-0138667, filed
on Dec. 20, 2011, in the Korean Intellectual Property Office, and
entitled: "Epoxy Resin Composition for Encapsulating Semiconductor
Device and Semiconductor Device Encapsulated with the Same," which
is incorporated by reference herein in its entirety.
BACKGROUND
[0002] 1. Field
[0003] Embodiments relate to an epoxy resin composition for
encapsulating a semiconductor device and a semiconductor device
encapsulated with the same.
[0004] 2. Description of the Related Art
[0005] Epoxy resin compositions for encapsulating semiconductor
devices should have good flame retardancy. UV94 V-0 is a criterion
for the flame retardancy of epoxy resin compositions required by
most semiconductor companies. Such a high level of flame retardancy
may be ensured by the use of halogenated flame retardants, e.g.,
brominated epoxy resins, and inorganic flame retardants, e.g.,
antimony trioxide, in the preparation of epoxy resin compositions
for encapsulating semiconductor devices.
[0006] However, epoxy resin compositions for encapsulating
semiconductor devices using halogenated flame retardants (to ensure
good flame retardancy) may produce toxic carcinogenic substances,
e.g., dioxin or difuran, upon incineration or fire and/or release
toxic gases, e.g., hydrogen bromide (HBr) and hydrogen chloride
(HCl), upon combustion. Such toxic substances and gases are harmful
to humans and may be corrosive to semiconductor chips, wires,
and/or lead frames.
[0007] Organic non-halogenated flame retardants and inorganic flame
retardants may be used. Phosphorus-based flame retardants, e.g.,
phosphazene and phosphoric acid esters, and other flame retardants,
such as nitrogen-containing resins, may be used as the organic
flame retardants. However, the nitrogen-containing resins may be
used in excessive amounts due to their poor flame retardancy. The
organic phosphorus-based flame retardants may have low reliability,
similar to inorganic phosphorus-based flame retardants.
[0008] Inorganic non-halogenated flame retardants, e.g., magnesium
hydroxide and zinc borate, may be used. However, the inorganic
flame retardants may be used in large amounts to ensure good flame
retardancy. In this case, the inorganic flame retardants may
deteriorate curability and continuous moldability of epoxy resin
compositions for encapsulating semiconductor devices. In order to
minimize such deterioration, a reduction in the amount of the
inorganic flame retardants used may be desirable. To this end,
epoxy resins and curing agents of the epoxy resin compositions for
encapsulating semiconductor devices may have a predetermined level
of flame retardancy.
SUMMARY
[0009] Embodiments are directed to an epoxy resin composition for
encapsulating a semiconductor device and a semiconductor device
encapsulated with the same
[0010] The embodiments may be realized by providing an epoxy resin
composition for encapsulating a semiconductor device, the
composition including an epoxy resin; an inorganic filler; a curing
accelerator; and a curing agent, the curing agent including a
compound having a multifunctional novolac structure including at
least one biphenyl moiety, the compound being represented by
Formula 1:
##STR00002##
[0011] wherein n is about 1 to about 10.
[0012] The epoxy resin composition may further include a
non-halogenated flame retardant.
[0013] The epoxy resin composition may include about 1 to about 13%
by weight of the epoxy resin, about 74 to about 94% by weight of
the inorganic filler, about 0.001 to about 1.5% by weight of the
curing accelerator, about 0.001 to about 10% by weight of the
non-halogenated flame retardant, and about 1 to about 15% by weight
of the curing agent.
[0014] The non-halogenated flame retardant may include at least one
of phosphazene, zinc borate, aluminum hydroxide, and magnesium
hydroxide.
[0015] The curing agent may have a hydroxyl equivalent weight of
about 100 g/eq to about 350 g/eq.
[0016] The curing agent may have a melt viscosity of about 0.08
poise to about 3 poise at 150.degree. C.
[0017] The curing agent may have a softening point of about 50 to
about 140.degree. C.
[0018] The compound represented by Formula 1 may be present in the
composition an amount of about 1 to about 15% by weight, based on a
total weight of the epoxy resin composition.
[0019] The curing agent may further include at least one additional
compound, the additional compound including two or more phenolic
hydroxyl groups.
[0020] The compound represented by Formula 1 may be present in the
composition in an amount of about 30% by weight or greater, based
on a total weight of the curing agent.
[0021] The additional compound may include at least one of a phenol
aralkyl type phenolic resin, a phenol novolac type phenolic resin,
a xyloc type phenolic resin, a cresol novolac type phenolic resin,
a naphthol type phenolic resin, a terpene type phenolic resin, a
multifunctional type phenolic resin, a multiaromatic phenolic
resin, a dicyclopentadiene type phenolic resin, a terpene-modified
phenolic resin, a dicyclopentadiene-modified phenolic resin, a
novolac type phenolic resin synthesized from bisphenol A and
resorcinol, a polyhydric phenolic compound, an acid anhydride, and
an aromatic amine.
[0022] The additional compound may include at least one of a phenol
aralkyl curing agent having a novolac structure represented by
Formula 6:
##STR00003##
[0023] wherein, in Formula 6, n is about 1 to about 7,
[0024] a xyloc curing agent represented by Formula 7:
##STR00004##
[0025] wherein, in Formula 7, n is about 1 to about 7, or
[0026] a multifunctional curing agent represented by Formula 8:
##STR00005##
[0027] wherein, in Formula 8, n is about 1 to about 7.
[0028] The epoxy resin and the curing agent may be included in the
composition in an amount such that a ratio of an epoxy equivalent
weight of the epoxy resin to a phenolic hydroxyl equivalent weight
of the curing agent is about 0.3:1 to about 2.5:1.
[0029] The embodiments may also be realized by providing a
semiconductor device encapsulated with the epoxy resin composition
according to an embodiment.
DETAILED DESCRIPTION
[0030] Example embodiments will now be described more fully
hereinafter; however, they may be embodied in different forms and
should not be construed as limited to the embodiments set forth
herein. Rather, these embodiments are provided so that this
disclosure will be thorough and complete, and will fully convey
exemplary implementations to those skilled in the art.
[0031] It will also be understood that when a layer or element is
referred to as being "on" another element, it can be directly on
the other element, or intervening elements may also be present.
[0032] An embodiment provides an epoxy resin composition. The epoxy
resin composition may include, e.g., an epoxy resin, a curing
agent, a curing accelerator, and an inorganic filler.
[0033] A. Epoxy Resin
[0034] The epoxy resin may be a suitable epoxy resin composition
for encapsulating semiconductor devices. For example, an epoxy
resin having two or more epoxy groups in the molecule may be used
without particular limitation. Examples of suitable epoxy resins
may include epoxy monomers, epoxy oligomers, and epoxy polymers.
The epoxy resins may be used alone or in combination of two or more
thereof.
[0035] In an implementation, the epoxy resin may include, e.g.,
epoxy resins obtained by epoxidation of condensation products of
phenol or alkyl phenols and hydroxybenzaldehyde, phenol novolac
type epoxy resins, cresol novolac type epoxy resins,
multifunctional epoxy resins, naphthol novolac type epoxy resins,
novolac type epoxy resins of bisphenol A/bisphenol F/bisphenol AD,
glycidyl ethers of bisphenol A/bisphenol F/bisphenol AD,
bishydroxybiphenyl type epoxy resins, dicyclopentadiene type epoxy
resins, biphenyl type epoxy resins, multiaromatic-modified epoxy
resins, bisphenol A type epoxy resins, ortho-cresol novolac type
epoxy resins, phenol aralkyl type epoxy resins, and naphthalene
type epoxy resins. The epoxy resins may be used alone or in
combination of two or more thereof.
[0036] The epoxy resin may be capable of imparting excellent
mechanical properties to the epoxy resin composition and/or an
encapsulant prepared from the composition. In an implementation,
the epoxy resin may include a phenol aralkyl type epoxy resin
having a novolac structure including at least one biphenyl moiety
in the molecule, as represented by Formula 2, below.
##STR00006##
[0037] In Formula 2, n may be an average of about 1 to about 7,
e.g., n may be about 1 to about 7.
[0038] In an implementation, the epoxy resin may include a biphenyl
type epoxy resin represented by Formula 3, below.
##STR00007##
[0039] In Formula 3, each R may be a methyl group, and n may be an
average of about 0 to about 7, e.g., n may be 0 to about 7.
[0040] In an implementation, the epoxy resin may include a xyloc
type epoxy resin represented by Formula 4, below.
##STR00008##
[0041] In Formula 4, n may be an average of about 1 to about 7,
e.g., n may be about 1 to about 7.
[0042] In an implementation, the epoxy resin may include a
multifunctional epoxy resin including naphthalene skeletons
represented by Formula 5, below.
##STR00009##
[0043] In Formula 5, n and m may each independently be an average
of about 0 to about 6, e.g., n may be 0 to about 6 and m may be 0
to about 6. In an implementation, the epoxy resin may include a
combination of any of the epoxy resins represented by Formulae
2-5.
[0044] The epoxy resin may be included in the composition in an
amount of about 1 to about 13% by weight, e.g., about 3 to about 9%
by weight, based on a total weight of the composition.
[0045] The epoxy resin may also be used in the form of an adduct,
e.g., a melt master batch obtained by pre-reacting with the curing
agent, the curing accelerator, and other additives, such as a
release agent and a coupling agent.
[0046] B. Curing Agent
[0047] The curing agent may include a compound having a
multifunctional novolac structure including at least one biphenyl
moiety, as represented by Formula 1, below.
##STR00010##
[0048] In Formula 1, n may be an average of about 1 to about 10,
e.g., n may be about 1 to about 10.
[0049] The presence of the curing agent may increase a crosslinking
density of the epoxy resin composition, leading to an increase in a
glass transition temperature of the epoxy resin composition.
Accordingly, the epoxy resin composition may undergo low shrinkage
on curing, which indicates good warpage resistance. The presence of
the biphenyl moiety in the curing agent may help ensure that the
epoxy resin composition exhibits excellent moisture resistance,
toughness, and crack resistance. In addition, the presence of the
biphenyl moiety may facilitate the formation of char layers upon
combustion, despite the relatively high crosslinking density of the
epoxy resin composition. Accordingly, the use of the curing agent
may help improve the flame retardancy of the epoxy resin
composition relative to another epoxy resin composition having a
similar glass transition temperature.
[0050] The curing agent may have a hydroxyl equivalent weight of
about 100 to about 350 g/eq, e.g., about 180 to about 300 g/eq.
Within this range, the epoxy resin composition may have a good
balance of curing shrinkage, curability, and flowability.
[0051] The curing agent may have a softening point of about 50 to
about 140.degree. C., e.g., about 60 to about 130.degree. C. The
curing agent may have a melt viscosity of about 0.08 to about 3
poise at 150.degree. C., e.g., about 0.1 to about 2.5 poise at
150.degree. C. Within the melt viscosity range defined above, the
flowability of the epoxy resin composition during melting, as well
as the moldability of the epoxy resin composition may not be
deteriorated.
[0052] The curing agent may be synthesized by a suitable method.
For example, the curing agent may be synthesized by mixing
4-phenylbenzaldehyde with phenol to prepare a solution, and
allowing the solution to react at about 80 to about 120.degree. C.
in the presence of an organic acid catalyst. However, the synthesis
of the curing agent is not limited to this method.
[0053] The epoxy resin composition may use the curing agent of
Formula 1 in combination with another suitable curing agent for
epoxy resin compositions.
[0054] The additional curing agent may include a suitable curing
agent used for the encapsulation of semiconductor devices and that
has two or more phenolic hydroxyl groups. The additional curing
agent may include, e.g., a monomer, an oligomers, a polymer, and/or
mixtures thereof.
[0055] Examples of curing agents that can be used in combination
with the curing agent of Formula 1 may include a phenol aralkyl
type phenolic resin, a phenol novolac type phenolic resin, a xyloc
type phenolic resin, a cresol novolac type phenolic resin, a
naphthol type phenolic resin, a terpene type phenolic resin, a
multifunctional type phenolic resin, a multiaromatic phenolic
resin, a dicyclopentadiene type phenolic resin, a terpene-modified
phenolic resin, a dicyclopentadiene-modified phenolic resin, a
novolac type phenolic resin synthesized from bisphenol A and
resorcinol, a polyhydric phenolic compound (including
tris(hydroxyphenyl)methane and dihydroxybiphenyl), an acid
anhydride (including maleic anhydride and phthalic anhydride), and
an aromatic amine (including metaphenylenediamine,
diaminodiphenylmethane, and diaminodiphenylsulfone).
[0056] In an implementation, the curing agent that can be used in
combination with the curing agent of Formula 1 may include a phenol
aralkyl type curing agent having a novolac structure including at
least one biphenyl moiety in the molecule, as represented by
Formula 6, below.
##STR00011##
[0057] In Formula 6, n may be an average of about 1 to about 7,
e.g., n may be about 1 to about 7.
[0058] In an implementation, the curing agent that can be used in
combination with the curing agent of Formula 1 may include a xyloc
type curing agent represented by Formula 7, below.
##STR00012##
[0059] In Formula 7, n may be an average of about 1 to about 7,
e.g., n may be about 1 to about 7.
[0060] In an implementation, the curing agent that can be used in
combination with the curing agent of Formula 1 may include a
multifunctional curing agent represented by Formula 8, below.
##STR00013##
[0061] In Formula 8, n may be an average of about 1 to about 7,
e.g., n may be about 1 to about 7.
[0062] In an implementation, the curing agent that can be used in
combination with the curing agent of Formula 1 may include a phenol
novolac type curing agent represented by Formula 9, below.
##STR00014##
[0063] In Formula 9, n may be an average of about 1 to about 7,
e.g., n may be about 1 to about 7.
[0064] In an implementation, the curing agent that can be used in
combination with the curing agent of Formula 1 may include a
combination or mixture of any of the curing agents represented by
Formulae 6-9.
[0065] When the curing agent of Formula 1 and the at least one
additional curing agent (selected from those mentioned above) are
used in the epoxy resin composition, the curing agent of Formula 1
may be included in the composition in an amount of at least about
30% by weight, e.g., at least about 50% by weight or about 60 to
about 100% by weight, based on a total weight of all curing agents.
Within this range, low curing shrinkage of the epoxy resin
composition can be ensured, and good adhesion strength,
reliability, and flowability of the epoxy resin composition may be
obtained.
[0066] The curing agent may also be used in the form of an adduct,
e.g., a melt master batch obtained by pre-reacting with the epoxy
resin, the curing accelerator, and other additives.
[0067] The epoxy resin and the curing agent may be included in the
composition in relative amounts such that a ratio of the epoxy
equivalent weight of the epoxy resin to the phenolic hydroxyl
equivalent weight of the curing agent is from about 0.3:1 to about
2.5:1, e.g., about 0.6:1 to about 1.5:1. Within this range, high
flowability of the epoxy resin composition may be ensured, without
extending curing time.
[0068] The curing agent may be included in the composition in an
amount of about 1 to about 15% by weight, e.g., about 2 to about
12% by weight, based on the weight of the epoxy resin composition.
Within this range, the flowability, flame retardancy, adhesion
strength, and reliability of the epoxy resin composition may be
improved.
[0069] C. Curing Accelerator
[0070] The curing accelerator may be a substance that helps promote
a reaction between the epoxy resin and the curing agent. The curing
accelerator may include a suitable curing accelerator, e.g., a
tertiary amine, an organometallic compound, an organophosphorus
compound, an imidazole compound, and/or a boron compound. Specific
examples of suitable tertiary amines may include
benzyldimethylamine, triethanolamine, triethylenediamine,
dimethylaminoethanol, tri(dimethylaminomethyl)phenol,
2-2-(dimethylaminomethyl)phenol, 2,4,6-tris(diaminomethyl)phenol,
and salts of tri-2-ethylhexanoic acid. Specific examples of
suitable organometallic compounds may include chromium
acetylacetonate, zinc acetylacetonate, and nickel acetylacetonate.
Specific examples of suitable organophosphorus compounds may
include tris(4-methoxy)phosphine, tetrabutylphosphonium bromide,
tetraphenylphosphonium bromide, phenylphosphine, diphenylphosphine,
triphenylphosphine, triphenylphosphine triphenylborane, and
triphenyl-phosphine-1,4-benzoquinone adducts. Specific examples of
suitable imidazole compounds may include 2-methylimidazole,
2-phenylimidazole, 2-aminoimidazole, 2-methyl-1-vinylimidazole,
2-ethyl-4-methylimidazole, and 2-heptadecylimidazole. Specific
examples of suitable boron compounds may include
tetraphenylphosphonium tetraphenylborate, triphenylphosphine
tetraphenylborate, tetraphenylboron salts,
trifluoroborane-n-hexylamine, trifluoroborane monoethylamine,
tetrafluoroborane triethylamine, and tetrafluoroborane amine. In
addition to these curing accelerators,
1,5-diazabicyclo[4.3.0]non-5-ene (DBN),
1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and phenol novolac resin
salts may be used.
[0071] The curing accelerator may also be used in the form of an
adduct obtained by pre-reacting with the epoxy resin and/or the
curing agent.
[0072] The curing accelerator may be included in the composition in
an amount of about 0.001 to about 1.5% by weight, e.g., about 0.01
to about 1% by weight, based on the total weight of the epoxy resin
composition. Within this range, curing time may not be extended and
high flowability of the epoxy resin composition may be ensured.
[0073] D. Inorganic Filler
[0074] The inorganic filler may help improve mechanical properties
of the epoxy resin composition and may help reduce stress in the
epoxy resin composition. Examples of suitable inorganic fillers may
include fused silica, crystalline silica, calcium carbonate,
magnesium carbonate, alumina, magnesia, clay, talc, calcium
silicate, titanium oxide, antimony oxide, and glass fiber. In an
implementation, the inorganic filler may include fused silica
having a low coefficient of linear expansion, in consideration of
stress reduction.
[0075] The fused silica may refer to amorphous silica having a
specific gravity not higher than about 2.3. The fused silica may be
prepared by, e.g., melting crystalline silica or may include
amorphous silica products synthesized from various raw
materials.
[0076] Before use, the inorganic filler may be surface treated with
at least one coupling agent selected from epoxysilanes,
aminosilanes, mercaptosilanes, alkylsilanes and alkoxysilanes.
[0077] There is no particular restriction as to the shape and
particle diameter of the inorganic filler, e.g., the fused silica.
For example, the inorganic filler may be spherical fused silica
having an average particle diameter of about 0.001 to about 30
.mu.m. In an implementation, the inorganic filler may include a
mixture of spherical fused silica products having different
particle diameters. The particle diameter of the inorganic filler
may also be adjusted to a maximum of, e.g., about 45 .mu.m, about
55 .mu.m, or about 75 .mu.m depending on the application of the
epoxy resin composition and the structure of a package to which the
epoxy resin composition is to be applied. For example, the
inorganic filler may include a mixture of first spherical fused
silica having an average particle diameter of about 15 to about 30
.mu.m and second spherical fused silica having an average particle
diameter of about 0.01 to about 10 .mu.m in a weight ratio of about
5:1 to about 10:1.
[0078] The inorganic filler may be included in a suitable amount,
depending on desired physical properties of the epoxy resin
composition, e.g., moldability, low-stress properties, and
high-temperature strength. In an implementation, the inorganic
filler may be included in the composition in an amount of about 70
to about 94% by weight, e.g., about 82 to about 92% by weight,
based on the weight of the epoxy resin composition. Within this
range, good flame retardancy, flowability, and reliability of the
epoxy resin composition may be ensured.
[0079] E. Flame Retardant
[0080] The epoxy resin composition of the present invention may
further include a flame retardant. For example, the flame retardant
may include a non-halogenated flame retardant.
[0081] The non-halogenated flame retardant may include, e.g., an
organic non-halogenated flame retardant, an inorganic
non-halogenated flame retardant, or a mixture thereof. Examples of
suitable non-halogenated flame retardants may include phosphazene,
zinc borate, aluminum hydroxide, and magnesium hydroxide. The flame
retardancy of the flame retardant may vary depending on various
factors, e.g., the content of the inorganic filler and the kind of
the curing agent. Thus, the flame retardant may be included in a
suitable amount, depending on the desired flame retardancy of the
epoxy resin composition. For example, when the inorganic filler is
included in an amount of about 70 to about 82% by weight, the flame
retardant may be included in an amount of about 3 to about 10% by
weight, based on the weight of the epoxy resin composition. In an
implementation, when the inorganic filler is included in an amount
of about 82 to about 94% by weight, the flame retardant may be
included in an amount of about 0 to about 3% by weight, based on
the weight of the epoxy resin composition. The amount of the flame
retardant included in the composition may not be determined only by
the amount of the inorganic filler, but may also be from about 0 to
about 10% by weight, based on the weight of the epoxy resin
composition.
[0082] In an implementation, the epoxy resin composition may
include, e.g., about 1 to about 13% by weight of the epoxy resin,
about 1 to about 15% by weight of the curing agent, about 0.001 to
about 1.5% by weight of the curing accelerator, about 74 to about
94% by weight of the inorganic filler, and about 0.001 to about 10%
by weight of the non-halogenated flame retardant.
[0083] F. Additives
[0084] The epoxy resin composition may further include one or more
additives selected from, e.g., colorants, coupling agents, release
agents, stress-relieving agents, crosslinking enhancers, and
leveling agents.
[0085] Examples of suitable colorants may include carbon black,
organic dyes, and inorganic dyes. Examples of suitable coupling
agents may include epoxysilanes, aminosilanes, mercaptosilanes,
alkylsilanes, and alkoxysilanes. Examples of suitable release
agents may include paraffin type waxes, ester type waxes, higher
fatty acids, metal salts of higher fatty acids, natural fatty
acids, and metal salts of natural fatty acids. Examples of suitable
stress-relieving agents may include modified silicone oils,
silicone elastomers, silicone powders, and silicone resins. The
additives may be included in an amount of about 0.1 to about 5.5%
by weight, based on the weight of the epoxy resin composition.
[0086] There epoxy resin composition may be prepared by a suitable
method. For example, the epoxy resin composition may be prepared by
the following procedure. First, all components of the composition
may be homogenized using a suitable mixer, such as a Henschel mixer
or a Redige mixer. The mixture may be melt-kneaded in a roll mill
or a kneader, cooled, and pulverized. Low-pressure transfer molding
may be used to encapsulate a semiconductor device with the epoxy
resin composition. Injection molding or casting may also be used to
mold the epoxy resin composition. Semiconductor devices that can be
fabricated by the method may include copper lead frames, iron lead
frames, iron lead frames pre-plated with at least one of nickel,
copper and palladium, and organic laminate frames.
[0087] Another embodiment provides a semiconductor device
encapsulated with the epoxy resin composition, e.g., with an
encapsulant prepared from the composition. The semiconductor device
may be encapsulated with the epoxy resin composition by a suitable
method.
[0088] The following Examples and Comparative Examples are provided
in order to highlight characteristics of one or more embodiments,
but it will be understood that the Examples and Comparative
Examples are not to be construed as limiting the scope of the
embodiments, nor are the Comparative Examples to be construed as
being outside the scope of the embodiments. Further, it will be
understood that the embodiments are not limited to the particular
details described in the Examples and Comparative Examples.
EXAMPLES
[0089] Detailed specifications of components used in Examples 1-3
and Comparative Examples 1-6 are as follows:
[0090] A. Epoxy Resins
[0091] A1: Phenol aralkyl type epoxy resin (NC-3000, Nippon
Kayaku)
[0092] A2: Multifunctional epoxy resin including naphthalene
skeletons (1-IP-4770, DIC)
[0093] B. Curing Agents
[0094] B1: Phenolic resin having a multifunctional novolac
structure (Formula 1, softening point=108.degree. C., hydroxyl
equivalent weight=204 g/eq.) synthesized by reaction of phenol and
4-phenylbenzaldehyde
[0095] B2: Phenol aralkyl type phenolic resin (MEH-7851SS, Meiwa
Kasei)
[0096] B3: Multifunctional phenolic resin (MEH-7500-35, Meiwa
Kasei)
[0097] B4: Phenol novolac type phenolic resin (HF-1M, Meiwa
Kasei)
[0098] C. Curing Accelerator
[0099] Triphenylphosphine (TPP, Hokko). The catalyst was added in
an amount of 3 parts per hundred resin (phr) relative to the epoxy
resin(s).
[0100] D. Inorganic Filler
[0101] Mixture of spherical fused silica having an average particle
diameter of 18 .mu.m and spherical fused silica having an average
particle diameter of 0.5 .mu.m in a weight ratio of 9:1
[0102] E. Flame retardant
[0103] Magnesium hydroxide (MGZ-6R, Sakai Chemical)
[0104] F1. Coupling agents
[0105] F11: Mercaptopropyltrimethoxysilane (KBM-803, Shinetsu)
[0106] F12: Methyltrimethoxysilane (SZ-6070, Dow Corning
Chemical)
[0107] F2. Colorant
[0108] Carbon black (MA-600, Matsushita Chemical)
[0109] F3. Release agent
[0110] Carnauba wax
Examples 1-3
[0111] The epoxy resins (A), the curing agents (B), the curing
accelerator (C), the inorganic filler (D), the flame retardant (E),
the coupling agents (F1), the colorant (F2), and the release agent
(F3) were added in accordance with the compositions shown in Table
1, below, homogenized using a Henschel mixer, melt-kneaded using a
continuous kneader at 95.degree. C., cooled, and pulverized to
prepare epoxy resin compositions for encapsulating semiconductor
devices.
Comparative Examples 1-6
[0112] Epoxy resin compositions for encapsulating semiconductor
devices were prepared in the same manner as in Examples 1-3, except
that the contents of the epoxy resins, the curing agents, the
curing accelerator, the inorganic filler, the flame retardant, the
coupling agents, the colorant, and the release agent were changed
as shown in Table 1.
TABLE-US-00001 TABLE 1 Example No. Comparative Example No. 1 2 3 1
2 3 4 5 6 A A1 6.67 -- 3.12 6.73 8.5 8.41 -- -- -- A2 -- 5.85 3.12
-- -- -- 5.93 7.82 7.72 B B1 5.13 5.97 5.58 -- -- -- -- -- -- B2 --
-- -- 5.06 -- -- 5.9 -- -- B3 -- -- -- -- 3.24 -- -- 3.95 -- B4 --
-- -- -- -- 3.33 -- -- 4.05 C 0.2 0.18 0.19 0.21 0.6 0.26 0.17 0.23
0.23 D 86.1 86.1 86.09 86.1 86.1 86.1 86.1 86.1 86.1 E 1 1 1 1 1 1
1 1 1 F1 F11 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 F12 0.2 0.2 0.2
0.2 0.2 0.2 0.2 0.2 0.2 F2 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 F3
0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Experimental Example 1:
Evaluation of physical properties of the epoxy resin
compositions
[0113] The epoxy resin compositions prepared in Examples 1-3 and
Comparative Examples 1-6 were evaluated for physical properties
shown in Table 2. The results are shown in Table 2, below.
[0114] Methods for Evaluation of Physical Properties
[0115] 1. Curing shrinkage: Each of the epoxy resin compositions
was molded using a transfer molding press in an ASTM mold for
flexural strength specimen construction at 175.degree. C. and 70
kgf/cm.sup.2 under the following conditions: transfer
pressure=1,000 psi, transfer speed=0.5-1 cm/s and curing time=120
sec. As a result of the molding, a specimen
(125.times.12.6.times.6.4 mm) was obtained. The specimen was
subjected to post-molding cure (PMC) in an oven at 170-180.degree.
C. for 4 hr, and cooled. The length of the specimen was
measured.
[0116] The curing shrinkage of the epoxy resin composition was
calculated by the following equation:
Curing Shrinkage=(Length of the mold at 175.degree. C.-Length of
the specimen)/(Length of the mold at 175.degree. C.).times.100
[0117] 2. Glass transition temperature was measured using a
thermomechanical analyzer (TMA) while heating at a rate of
10.degree. C./min from 25.degree. C. to 300.degree. C.
[0118] 3. Moisture absorption: Each of the resin compositions
prepared in Examples 1-3 and Comparative Examples 1-6 was molded at
a mold temperature of 170-180.degree. C., a pressure of 70
kg/cm.sup.2, a transfer pressure of 1,000 psi and a transfer speed
of 0.5-1 cm/s for a curing time of 120 sec to obtain a cured
specimen in the form of a disk having a diameter of 50 mm and a
thickness of 1 mm. The specimen was subjected to post-molding cure
(PMC) in an oven at 170-180.degree. C. for 4 hr and allowed to
stand at 85.degree. C. and 85 RH % for 168 hr. The weights of the
specimen before and after moisture absorption were measured. The
moisture absorption of the resin composition was calculated by the
following equation:
Moisture absorption(%)=(Weight of the specimen after moisture
absorption-Weight of the specimen before moisture
absorption)/(Weight of the specimen before moisture
absorption).times.100
[0119] 4. Flame retardancy was evaluated using a 1/8 inch thick
specimen according to the UL94 V-0 standard.
[0120] 5. Adhesive strength: A copper metal device having a
specification adapted to a mold for adhesive strength measurement
was prepared as a test piece. Each of the resin compositions
prepared in Examples 1-3 and Comparative Examples 1-6 was molded on
the test piece at a mold temperature of 170-180.degree. C., a
pressure of 70 kgf/cm.sup.2, a transfer pressure of 1,000 psi and a
transfer speed of 0.5-1 cm/s for a curing time of 120 sec to obtain
a cured specimen. The specimen was subjected to post-molding cure
(PMC) in an oven at 170-180.degree. C. for 4 hr. The area of the
epoxy resin composition in contact with the specimen was 40.+-.1
mm.sup.2. The adhesive strength of the epoxy resin composition was
measured using a universal testing machine (UTM). 12 specimens were
produced for each composition. After the measurement procedure was
repeated, the measured adhesive strength values were averaged.
[0121] 6. Warpage resistance: Each of the compositions prepared in
Examples 1-3 and Comparative Examples 1-6 was transfer molded on a
copper metal device using a multi plunger system (MPS) at
175.degree. C. for 70 sec to construct an exposed thin quad flat
package (eTQFP) having a width of 20 mm, a length of 20 mm and a
thickness of 1 mm. The package was subjected to post molding cure
at 175.degree. C. for 4 hr and cooled to 25.degree. C. Thereafter,
a height difference between the diagonal center of the upper
surface of the package and the highest corner of the package was
measured. A smaller height difference indicates better warpage
resistance.
[0122] 7. Reliability: The eTQFP package for warpage resistance
evaluation was dried at 125.degree. C. for 24 hr. After 5 cycles of
thermal shock testing (1 cycle refers to a series of exposures of
the package to -65.degree. C. for 10 min, 25.degree. C. for 10 min,
and 150.degree. C. for 10 min), the package was allowed to stand at
85.degree. C. and 60% RH for 168 hr and passed through IR reflow
three times at 260.degree. C. for 30 sec (preconditioning). After
preconditioning, the occurrence of external cracks in the package
was observed using an optical microscope, and the occurrence of
peeling between the epoxy resin composition and the lead frame was
evaluated by scanning acoustic microscopy (C-SAM) as a
non-destructive testing method. External cracks of the package or
peeling between the epoxy resin composition and the lead frame
cannot guarantee reliability of the package.
TABLE-US-00002 TABLE 2 Example No. Comparative Example No. 1 2 3 1
2 3 4 5 6 Basic physical Curing shrinkage (%) 0.21 0.13 0.18 0.27
0.24 0.24 0.23 0.18 0.18 properties Glass transition temp.
(.degree. C.) 164 174 170 135 160 161 153 172 174 Moisture
absorption (wt %) 0.18 0.20 0.20 0.21 0.26 0.27 0.22 0.27 0.27
Flame retardancy V-0 V-0 V-0 V-0 V-1 V-1 V-0 V-1 V-1 Adhesive
strength (kg.sub.f) 70 60 65 68 58 57 58 52 48 Evaluation of
Warpage (mil) 1.45 0.82 1.22 2.40 1.72 1.84 1.67 1.24 1.23 packages
Reliability Number of external 0 0 0 0 0 0 0 0 0 cracks Number of
peelings 0 0 0 0 22 22 3 22 22 Total number of 22 22 22 22 22 22 22
22 22 semiconductors tested
[0123] The composition of Comparative Example 1 (using the phenol
aralkyl type epoxy resin and the phenol aralkyl type phenolic
resin) had a low moisture absorption and showed excellent adhesion
properties. The results of evaluation for the package indicate that
high reliability could be ensured. However, the composition showed
poor warpage resistance of the package due to its low glass
transition temperature and high curing shrinkage. The compositions
of Comparative Examples 2-3 (each using the phenol aralkyl type
epoxy resin and the multifunctional phenolic resin or the phenol
novolac type phenolic resin), showed improved warpage resistance
due to their higher glass transition temperatures and lower curing
shrinkages than the composition of Comparative Example 1 (using the
phenol aralkyl type phenolic resin). However, high reliability of
the packages could not be ensured due to the high moisture
absorptions, and good flame retardancy could not be ensured by the
use of the flame retardant in a small amount.
[0124] The compositions of Comparative Examples 4-6 (each using the
multifunctional epoxy resin including naphthalene skeletons),
showed good warpage resistance due to their higher glass transition
temperatures and lower curing shrinkages than the compositions of
Comparative Examples 1-3 (each using the phenol aralkyl type epoxy
resin). However, high reliability of the packages could not be
ensured due to the high moisture absorptions and low adhesive
strengths.
[0125] The composition of Example 1 (using the curing agent having
a multifunctional novolac structure including at least one biphenyl
moiety) had a glass transition temperature similar to or higher
than those of the compositions of Comparative Examples 1-3 (using
different curing agents) and had a lower curing shrinkage than the
compositions of Comparative Examples 1-3. These results indicate
better warpage resistance of the package. In addition, the
composition of Example 1 showed good peeling resistance due to its
low moisture absorption and high adhesive strength, ensuring high
package reliability. Furthermore, the composition of Example 1
could ensure good flame retardancy despite the low content of the
flame retardant.
[0126] The composition of Example 2 had a glass transition
temperature similar to or higher than those of the compositions of
Comparative Examples 4-6 (using different curing agents) and had a
lower curing shrinkage than the compositions of Comparative
Examples 4-6. These results indicate better warpage resistance of
the package. In addition, the composition of Example 2 could ensure
high package reliability due to its low moisture absorption and
high adhesive strength.
[0127] By way of summation and review, with the recent distribution
of small-sized and thin portable digital devices, semiconductor
packages mounted in the digital devices have become increasingly
lightweight and small, to increase packaging density per unit
volume. In the lightweight and small packages, differences in
coefficients of thermal expansion of semiconductor chips, lead
frames, and epoxy resin compositions constituting the packages, and
thermal shrinkage and curing shrinkage of the epoxy resin
compositions encapsulating the packages may cause the packages to
warp. Such warpage of the packages may cause defects during
soldering in semiconductor post-processes, leading to the
occurrence of electrical defects. Thus, warpage resistant epoxy
resin compositions for encapsulating semiconductor devices may be
desirable.
[0128] Improving the warpage resistance of epoxy resin compositions
may be associated with increased glass transition temperatures and
decreased curing shrinkage of the epoxy resin compositions.
[0129] A semiconductor package may be exposed to high temperatures
(e.g., about 260.degree. C.) in the course of mounting on a
substrate. This exposure may cause moisture present in the package
to rapidly expand, leading to internal peeling and external
cracking of the package. Reducing the moisture absorption of an
epoxy resin composition for encapsulating a semiconductor device in
order to protect the package from peeling and cracks may be
desirable to achieve high reliability of the package. When the
glass transition temperature of the epoxy resin composition is
increased to achieve improved warpage resistance, an inevitable
increase in the moisture absorption of the composition may result
in poor reliability of the package. Accordingly, increasing the
glass transition temperature of the package with poor reliability
for the purpose of achieving improved warpage resistance may be
limited.
[0130] Reducing the curing shrinkage of an epoxy resin composition
may include increasing an amount of an inorganic filler in the
epoxy resin composition. However, this approach may result in low
flowability of the epoxy resin composition. Accordingly, increasing
the content of the inorganic filler may also be essentially
limited.
[0131] Accordingly, the embodiments provide an epoxy resin
compositions for encapsulating semiconductor devices that have high
reliability and good flowability while possessing excellent warpage
resistance and that can ensure good flame retardancy even without
the use of halogenated flame retardants.
[0132] The embodiments provide an epoxy resin composition for
encapsulating a semiconductor device that includes a curing agent
having a particular structure.
[0133] The embodiments provide an epoxy resin composition that has
improved warpage resistance, good adhesion to other constituent
materials of a semiconductor package, high reliability, and good
flame retardancy without the need to include a halogenated flame
retardant.
[0134] The epoxy resin composition according to an embodiment may
have improved warpage resistance due to its high glass transition
temperature and low curing shrinkage. In addition, the epoxy resin
composition may be highly reliable due to its good adhesiveness and
low moisture absorption. Furthermore, the epoxy resin composition
may ensure good flame retardancy without the need to use a
halogenated flame retardant and thus may be environmentally
friendly.
[0135] Example embodiments have been disclosed herein, and although
specific terms are employed, they are used and are to be
interpreted in a generic and descriptive sense only and not for
purpose of limitation. Accordingly, it will be understood by those
of skill in the art that various changes in form and details may be
made without departing from the spirit and scope of the present
invention as set forth in the following claims.
* * * * *